Error: Update the Android Gradle plugin to version 3.2.0 or higher / generate Flutter signed APK

 4

Finaly solve this problem. I trid all that way mentioned in the question and stell that dump error  it doesn't look logical. but its work for me. I closed project in android studio then open android folder at my project folder in new a android studio window,

like this below 

then it take long time for downloading, analyzing, or... something,

you can see the layout is not same as main project .... 

also build menu has more options... 

after that tried to build app bundle and everything is good. I think generating app bundles is not possible in main project file. we need to switch to android folder and generating it.

after all these I searched youtube generate app bundle android studio flutter https://www.youtube.com/watch?v=g0GNuoCOtaQ in this building app bundle in another way that doesn't have these headaches